Para quem tiver com problemas pra configurar o Spring Security...

Lendo essa documentação: https://docs.spring.io/spring-security/site/docs/4.2.0.RELEASE/reference/htmlsingle/#maven-bom

Informa que se utilizar o spring-framework-bom na versão 4.3.4.RELEASE consegue administrar versões mais antigas, como 4.0. (incluso dentro de um dependencyManagement), porém no meu caso bastou apenas colocar acima das outras spring-securitys pra funcionar!

<!-- Spring Security -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-framework-bom</artifactId>
            <version>4.3.4.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-config</artifactId>
            <version>4.0.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-taglibs</artifactId>
            <version>4.0.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <version>4.0.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-core</artifactId>
            <version>4.0.1.RELEASE</version>
        </dependency>
    </dependencies>
    <repositories>
        <!-- ... possibly other repository elements ... -->
        <repository>
            <id>spring-milestone</id>
            <name>Spring Milestone Repository</name>
            <url>http://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>